119.A 58-year-old Caucasian woman is seen in the endocrine clinic. She
has been followed for type I diabetes for the past decade. She sustained a
Colles’ fracture last year when she fell over the hose while watering the gar-
den. She took hormone replacement therapy (HRT) for 3 years at the start of
menopause, but was taken off HRT 5 years ago because of her concerns about
ovarian cancer. She drinks three glasses of milk a day and eats other dairy
products frequently. She drinks socially, a drink, a glass of wine, or a beer
twice/week. She does not smoke. She once was a “runner,” but now walks
2 miles twice/week when weather permits. She is 5 ft 4 in. and she weighs
122 lb.Her height has decreased by an inch over the past 5 years and her
weight has increased by 12 lb. CBC and blood chemistries are normal. Her “T”
score on dual-energy absorptiometry (DXA) is -2 for spine and -2.5 for hip.
Bisphosphonates are prescribed. Which of the following is the most likely
mechanism of action for the bisphosphonates?
a. Inhibition of osteoblastic activity
b. Increased RANK-L secretion by osteoblasts
c. Increased M-CSF secretion by osteoblasts
d. Apoptosis of osteoclasts
e. Increased RANK expression by osteoclasts
120.A 12-year-old boy who has grown 3 in. in the past 2 months presents
with pain and swelling in his femur just above the knee. Any exercise results
in intense pain, and the boy now walks with a limp. X-ray shows a fracture at
the distal end of the right femur. Overall, the bone appears immature in the
distal femur and there is increased density extending into the metaphysis.
There appears to be a soft tissue mass expanding outside the bone. There is
also some cortical bone destruction above the lateral condyle. A CT scan
shows bone-forming cells in the lung. Once the osteosarcoma cells reach the
lungs, enter the lung parenchyma, and clonally expand, they produce bone.
In that process, the tumor cells synthesize which of the following?
a. Type III collagen
b. Type II collagen
c. Acid phosphatase
d. Alkaline phosphatase
e. Elastin
Specialized Connective Tissues: Bone and Cartilage 203